Variable pitch sheave



March 3l, 1953 l J. N.- BRowNlNG 2,633,031

VARIABLE PICH SHEAVE Fild'Jan. 24, 1951 rraRA/EYJ Patented Mar. 31, 1953 VARIABLE PITCH SHEAVE John N. Browning, Maysville, Ky., assignor to Browning Manufacturing Company,

Inc.,

Maysville, Ky., a corporation of Kentucky Application January 24,1951, Serial No. 207,584

Z Claims. l

The invention relates to novel and improved variable pitch sheave construction, wherein pro vision is made for variation in the relative distance between the belt-containing members. The sheave is particularly designed for V-belts, and the variability resides in the novel and improved means for controlling and readily fixing and maintaining the distance between the angular sides of the belt groove. Therein lies the object of the present invention.

Other objects and advantages will be apparent from a study of the following description,in conjunction with the accompanying drawing, in which:

Fig. 1 is a view, partly in section and partly in plan, showing a sheave constructed in accordance with the teaching of the present invention.

Figs. 2, 3, and 4 are sectional views taken on the lines 2-2, 3--3 and 4--4 of Fig. l, Fig. 4 being somewhat enlarged.

It will be understood that the embodiment here shown is merely one exemplification of the invention, sincey as will appear obvious upon a study of the following description, other` embodiments can be constructed embodying the invention which will respond to the terms of the appended claims. Merely to illustrate this, the sheave shown in the drawings is a compound one having two belt grooves. One, three, four, or more grooves could be provided While still embodying the invention.

Referring now to the drawings, there is shown, iragmentarily, a motor II which drives a shaft I2 upon which is iixed a sheave assembly indicated generally by referencecharacter I3. The sheave of course could be driven from another power source, not shown, in which case shaft I2 would be driven by the sheave, instead of driving the sheave, and member II could be a generator instead of a motor.

The sheave comprises what I will term for convenience a fixed member I 4, centrally disposed, and cooperable with a pair of movable members I and I5 which are placed one on each side of the xed member, and each spaced therefrom. The distance between each movable member and the fixed member may be varied as follows:

Fixed member I4 has a pair of opposed, axially aligned hubs Ita and libwhich are centrally bored to receive shaft I2 (Fig. 4) there being alignable grooves in the shaft and hubs for the reception of a key I1 whereby member I4 is fixed to rotate with shaft I2. The hubs are externally threaded, and the movable members are provided with bored bosses I5a and Ilia, internally threaded for convenient endwise movement, each on a re- (Cl. 'Z4-230.17)

2 spective hub. When suitable predetermined distances have been established by such endwise movement, the movable-members are secured in place in the following novel and improved fashion.

The hubs Ida and I 4b are chordally attened at diametrically opposed zones F, and member I4 is perforated at opposed locations- I8 and I 8a in longitudinal alignment with said flattened zones. The movable members are provided with key grooves 20 and 2| which are alignable with said flattened zones and said perforations I8 and Ita at each rotational point of said movable members. At any such predetermined aligned postion a attened key IS is insertible through grooves 20 and 2| and aperture I8 or 18a (through I8 as shown in Fig. 4) and set screws 23 are then advanced to clamp the assembly in said predetermined position. The opposed complementary peripheries of members I4, I5, and I6 are tapered, at T, to receive conventional V- belts 24 and 25, and it will be apparent that variation in the spacing between I4 and I5, for example, will result in variation of the radial distance of belt 24 from the axis of shaft rotation with consequent variation in the arc of effective belt contact, so as to, in effect, vary the pitch of the sheave. The same is true, of course, with respect to belt 25.

Since the flat key I9 lies in a fitted groove in each of the movable members I5 and I6 it is obviously impossible to rotate the members either with respect to each other without removing the key I9. 'Since the key I9 has one face in contact with the ilattened zones F, the members l5 and E6 cannot be rotated with respect to hubs I 4a and I4b while the key I9 is in place. The arrangement is greatly superior to the use of a set screw in a hub which binds on a shaft, since the set screw may gouge the shaft with resultant undesirable free play. It is superior to an ordinary key and groove assembly since such last named key cannot be readily removed for quick adjustments. When the present set screws 23 are advanced to tightened position they have no tendency to gouge key I9 because they are not rotatable with respect to the contacted surface of the flat key, and key I9 is obviously not rotatable around the hubs because the dat contacting surfaces are not coplanar with a cylindrical surface of rotation around the rotational axis. Actually the main purpose of the set screwsis to hold key I 9 in pre determined position until it becomes desirable to change the belt groove adjustments.

While we have described the hubs I4a and I4b as having diametrically opposed, flattened por- 3 tions, it is obvious that a plurality of peripherally spaced, attened portions could be provided, spaced in any desirable way, such as at 90 intervals, so as to multiply the number of potential stopping places, to thereby give a greater sensitivity in the adjustment of groove width. Such an arrangement is comprehended within the coverage of the appended claims.

What I claim is:

1. A variable pitch sheave comprising a discoidal central member, the peripheral edge face portions being convergently beveled, said central member having opposed hubs extending axially away from said member, a pair of movable discs each having a central threaded bore, the outer peripheries of said hubs being threaded so as to each receive one of said discs thereon, such threaded engagement permitting each of said discs to be rotatably advanced towards, and retracted from, said central member, each said hub having a longitudinally attened zone thereon, each said disk Vhaving a keyway on its internal periphery adjacent said hub and alignable, by disc rotation, with said flattened portions, a key longitudinally insertible in said keyway and having its external face in contact With said flattened portions whereby, when said key is in such position, to prevent relative rotation between the disc and the hub, each said disc having a peripheral edge face portion beveled to match the bevel on the adjacent side of the discoidal member, said bevels being matched whereby to aord seats for a pair of V-belts, one

each side of said central member, said flattened portions of the respective hubs being in longitudinal planar alignment, said central member having an aperture therethrough in alignment with both said attened portions, whereby to permit a single key to extend completely along the iiattened portions of both said hubs simultaneously.

2. A variable pitch sheave as defined in claim 1 wherein each said hub has an additional flattened portion, the attened portions on each hub being located one on each side of each hub at diametrically opposed points, whereby the key groove of each said movable disc may be brought to fixable registry at either one of two opposed positions.

JOHN N. BROWNING.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 650,154 Owens May-22, 1900 784,014 Steel Feb. 28, 1905 2,151,045 Ploehn Mar. 21, 1939 2,324,681 Dekker July 20, 1943 2,549,823 Kost Apr. 24, 1951 FOREIGN PATENTS Number Country Date 872,177 France June l, 1942 

